Why are you eating so much fish oil? Is it to offset any n6's in vegetable oil and fatty grain-fed meats? If coconut oil is too out there for your parents, you could always propose EV olive oil. Even CW marks this oil as extremely healthy.
And per your question about olive oil changing the taste of chili - probably not, since chili has so much of its own spices and meaty flavor that will effectively mask any oil you're using to cook it in.